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1 (* Copyright (c) 2008, Adam Chlipala
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2 * All rights reserved.
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3 *
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4 * Redistribution and use in source and binary forms, with or without
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5 * modification, are permitted provided that the following conditions are met:
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6 *
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7 * - Redistributions of source code must retain the above copyright notice,
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8 * this list of conditions and the following disclaimer.
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9 * - Redistributions in binary form must reproduce the above copyright notice,
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10 * this list of conditions and the following disclaimer in the documentation
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11 * and/or other materials provided with the distribution.
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12 * - The names of contributors may not be used to endorse or promote products
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13 * derived from this software without specific prior written permission.
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14 *
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15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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18 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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19 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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25 * POSSIBILITY OF SUCH DAMAGE.
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26 *)
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27
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28 structure Search :> SEARCH = struct
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29
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30 datatype ('state, 'abort) result =
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31 Return of 'abort
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32 | Continue of 'state
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33
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34 type ('data, 'state, 'abort) mapfold_arg =
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35 'data * 'state -> ('data * 'state, 'abort) result
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36
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37 type ('data, 'state, 'abort) mapfolder =
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38 'data -> 'state -> ('data * 'state, 'abort) result
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39
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40 fun return2 v acc = Continue (v, acc)
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41
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42 fun map (r, f) =
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43 case r of
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44 Continue acc => Continue (f acc)
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45 | Return x => Return x
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46
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47 fun map2 (r, f) acc =
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48 case r acc of
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49 Continue (x, acc) => Continue (f x, acc)
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50 | Return x => Return x
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51
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52 fun bind (r, f) =
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53 case r of
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54 Continue acc => f acc
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55 | Return x => Return x
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56
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57 fun bind2 (r, f) acc =
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58 case r acc of
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59 Continue (x, acc) => f x acc
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60 | Return x => Return x
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61
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62 fun bindP (r, f) =
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63 case r of
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64 Continue ((x, pos), acc) =>
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65 map (f (x, acc),
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66 fn (x', acc') =>
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67 ((x', pos), acc'))
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68 | Return x => Return x
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69
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70 end
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